Optimisation of the preparation of an Al-pillared clay: thermal stability and surface acidity

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• 作者：Mrad ; Ihsan ; Ghorbel ; Abdelhamid ; Tichit ; Didier ; Lambert ; Jean-Franç ; ois
• 关键词：intercalation ; pillared clays ; surface acidity ; hydroxilic surface groups
• 刊名：Applied Clay Science
• 出版年：1997
• 期刊代码：5_01691317
• 类别：ms
• 出版时间：October, 1997
• 卷：12
• 期：4
• 页码：349-364
• 文件大小：812 K

摘要

The intercalation of montmorillonite by aluminium requires the use of aluminium chloride as a precursor for the intercalation solution. The best samples were obtained with an ratio = 2, a pH of 5.6 and an Al/clay ratio = 5 mmol/g. High surface area materials were obtained with good thermal stability after calcination at 773 K. A study of the acidity of surface groups showed that the Al₁₃ polycation is transformed into a specific form of Al oxyhydroxide with amphoteric properties. The data, when treated in the ‘1 site, 2 pK’ model, may be interpreted by the existence of surface species of type {AlOH(OH₂)}, having two constants of deprotonation K_a1 = 10⁻⁵ and K_a2 = 0.32 · 10⁻⁶. An alternate treatment in terms of the ‘multisite, 1 pK’ model recently developed by Jagiello et al. is also discussed.